Supercooled liquid nitrogen cooling circulation system

Abstract

The invention discloses a supercooled liquid nitrogen cooling circulation system which comprises a container containing a refrigerant and a circulation pipeline partially located in the container, at least part of the circulation pipeline is located below the liquid level where the refrigerant is located in the container, and the circulation pipeline is connected with load equipment and provides cooling capacity for the load equipment. Purging and vacuumizing pipelines are connected to the circulating pipelines located at the upstream and downstream of the load equipment, and adjusting pieces capable of adjusting the cold mass flow in the circulating pipelines are arranged on the circulating pipelines. According to the invention, through the arrangement of the purging and vacuumizing pipelines, the circulating pipeline between the two purging and vacuumizing pipelines and the replaced load equipment can be purged and vacuumized through the two purging and vacuumizing pipelines when the load equipment is replaced; and refrigerant consumption caused by replacement of load equipment after temperature returning of the whole circulating pipeline is avoided.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration and cryogenic technology, and more particularly to a supercooled liquid nitrogen cooling circulation system. Background Art

[0002] As people's research on life science and physics experiments continues to deepen, such as in the fields of superconductivity and quantum computing, as well as the development of industries such as electronics, semiconductors and precision instruments, more liquid nitrogen supply equipment is needed to provide a continuous and stable low-temperature environment. As a liquid nitrogen supply device, the intelligent liquid nitrogen circulation unit can automatically control the supply flow of liquid nitrogen and set the temperature of the liquid nitrogen fluid according to user needs. Its main functions include: refrigeration, low-temperature storage and transportation, liquid nitrogen supply, safety control, etc. It can provide a stable and reliable low-temperature environment for various experiments and tests, and can also be used for cryopreservation and transportation in the fields of medicine and biotechnology. For example, it can freeze biological samples at extremely low temperatures, thereby achieving long-term preservation and maintaining the original state of the samples, which is of great significance for biomedical research, germplasm preservation, and protection of animal and plant genetic resources. The intelligent liquid nitrogen circulation unit has excellent performance and safety assurance. It is not only widely used in scientific research, but also can bring practical benefits and application value to industries such as industry, medicine and environment. It can ensure the normal operation of experimental equipment and extend its service life. It is an indispensable part of modern research and experimental equipment; but the liquid nitrogen circulation unit in the prior art has the following disadvantages:

[0003] (1) The liquid nitrogen in the existing system will vaporize during the cooling process of the load equipment, resulting in an increase in flow rate and flow resistance, and a deterioration in heat exchange effect;

[0004] (2) The temperature fluctuation of liquid nitrogen supply is large, which is not conducive to the stable operation of low-temperature demand equipment;

[0005] (3) The existing device cannot automatically evacuate, purge and replenish fluid, and requires manual operation, which is somewhat dangerous. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to reduce the loss of liquid nitrogen caused by system temperature recovery when replacing equipment.

[0007] The present invention solves the above technical problems through the following technical means: a supercooled liquid nitrogen cooling circulation system, comprising a container containing a refrigerant and a circulation pipeline partially located in the container, wherein the circulation pipeline is at least partially located below the liquid level of the refrigerant in the container, the circulation pipeline is connected to a load device and provides cooling for it, the circulation pipelines located upstream and downstream of the load device are connected to purge and vacuum pipelines, and the circulation pipeline is provided with a regulating member capable of regulating the flow rate of cold mass in the circulation pipeline.

[0008] By setting up the purging and vacuuming pipelines, when replacing the load equipment, the circulation pipeline between the two purging and vacuuming pipelines and the replaced load equipment can be purged and vacuumed through the two purging and vacuuming pipelines, thereby avoiding the consumption of refrigerant caused by warming up the entire circulation pipeline and then replacing the load equipment.

[0009] As a preferred technical solution, it also includes a liquid replenishment pipeline and a buffer tank. The liquid replenishment pipeline is connected to the circulation pipeline through the buffer tank. The buffer tank is also provided with a pressure stabilizing component. The pressure stabilizing component can keep the refrigerant in the circulation pipeline in a supercooled state. The liquid replenishment pipeline is also the same as the container.

[0010] As a preferred technical solution, a heat exchanger is connected to the circulation pipeline, and the circulation pipeline includes a liquid supply pipeline and a liquid return pipeline that are connected to each other. One end of the liquid supply pipeline is connected to one end of the heat exchanger, and the other end is connected to the input end of the load device. One end of the liquid return pipeline is connected to the output end of the load device, and the other end is connected to the other end of the heat exchanger.

[0011] As a preferred technical solution, the regulating member comprises a liquid nitrogen circulation pump arranged on the circulation pipeline, and a second filter is also arranged on the circulation pipeline, and the second filter is located upstream of the liquid nitrogen circulation pump.

[0012] As a preferred technical solution, the regulating member includes a bypass line, one end of the bypass line is connected to the liquid supply line, and the other end of the bypass line is connected to the liquid return line, and the end of the bypass line connected to the liquid supply line is located upstream of the load device, and the end of the bypass line connected to the liquid return line is located downstream of the load device.

[0013] As a preferred technical solution, the voltage stabilizing component includes a low-temperature heating resistor arranged in a buffer tank, and the buffer tank is also provided with a buffer tank level gauge and a pressure sensor, and a level gauge is provided in the container.

[0014] As a preferred technical solution, the pressure stabilizing assembly includes a pressurizing pipeline and a pressure relief pipeline connected to the buffer tank, and the pressurizing pipeline and the pressure relief pipeline are both provided with control valves.

[0015] As a preferred technical solution, the container is also connected to an exhaust pipeline, which is in communication with the container and is provided with a second temperature sensor and a nitrogen exhaust heater.

[0016] As a preferred technical solution, the purge and vacuum pipeline includes a first purge and vacuum pipeline located upstream of the load device and a second purge and vacuum pipeline located downstream of the load device, wherein the first purge and vacuum pipeline is provided with a purge and vacuum interface three, and the second purge and vacuum pipeline is provided with a ball valve two, a purge and vacuum interface two, and a safety valve three.

[0017] As a preferred technical solution, the circulation pipeline is also connected to a liquid nitrogen discharge pipeline, a low-temperature switch valve 4 is provided on the liquid nitrogen discharge pipeline, and the output end of the liquid nitrogen discharge pipeline is connected to the inner cavity of the container.

[0018] The beneficial effects of the present invention are:

[0019] (1) In the present invention, by setting up the purging and vacuuming pipelines, when replacing the load equipment, the circulation pipeline between the two purging and vacuuming pipelines and the replaced load equipment can be purged and vacuumed through the two purging and vacuuming pipelines, thereby avoiding the consumption of refrigerant caused by the whole circulation pipeline being warmed up and then replacing the load equipment. At the same time, it is also possible to achieve rapid warming up of the equipment by blowing air separately. The purging of the system can be realized automatically by the control system, which improves efficiency and reduces the risk of human operation.

[0020] (2) In the present invention, by setting up the bypass pipeline, a self-check can be performed before connecting to the load equipment, and the load equipment can be connected after the self-check is passed, thereby avoiding damage to the load equipment. By setting up the low-temperature regulating valve 2, the flow in the circulation pipeline can be adjusted, thereby reducing the temperature fluctuation of the liquid nitrogen supply.

[0021] (3) In the present invention, the liquid nitrogen can be heated by the low-temperature heating resistor in the buffer tank, thereby increasing the boiling point, maintaining the liquid nitrogen below the boiling point, and always keeping it in a supercooled state, thereby preventing the liquid nitrogen from vaporizing. At the same time, helium can also be introduced. The boiling point of helium is very low and it will always be a gas in the liquid nitrogen temperature range. It is used to quickly pressurize the liquid nitrogen, thereby ensuring that the liquid nitrogen is always in a supercooled state. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the overall structure provided for an embodiment of the present invention;

[0023] Figure numbers: 1. Dewar tank level gauge; 2. Temperature sensor 1; 3. Helium inlet; 4. Electric valve 1; 5. Ball valve 1; 6. Purge and vacuum interface 1; 7. Safety bursting membrane 1; 8. Safety valve 1; 9. Liquid nitrogen supply pipe; 10. Filter 1; 11. Low-temperature regulating valve 1; 12. Liquid nitrogen circulation pump; 13. Low-temperature heating resistor; 14. Low-temperature switch valve 1; 15. Low-temperature switch valve 2; 16. Pressure sensor 1; 17. Helium outlet; 18. Electric valve 2; 19. Safety valve 2; 20. Nitrogen outlet heater; 21. Temperature sensor 2; 22. Ball valve 2; 23. Purge and vacuum Interface 2; 24. Safety bursting membrane 2; 25. Safety valve 3; 26. Ball valve 3; 27. Purge and vacuum interface 3; 28. Pressure sensor 2; 29. ​​Low-temperature switch valve 4; 30. Low-temperature switch valve 5; 31. Flow meter 1; 32. Temperature sensor 3; 33. Low-temperature regulating valve 2; 34. Flow meter 2; 35. Low-temperature switch valve 3; 36. Temperature sensor 4; 37. Temperature sensor 5; 38. Heat exchanger; 39. Load equipment; 40. Dewar tank; 41. Filter 2; 42. Buffer tank level gauge; 43. Buffer tank; 44. Bypass pipeline; 45. Liquid supply pipeline; 46. Liquid return pipeline. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1A supercooled liquid nitrogen cooling circulation system comprises a container containing a refrigerant and a circulation pipeline partially located in the container, a buffer tank 43, a liquid replenishment pipeline, an exhaust pipeline, a liquid nitrogen exhaust pipeline, and a controller. The circulation pipeline is at least partially located below the liquid level of the refrigerant in the container. The circulation pipeline is connected to a load device 39 and provides cooling for it. The circulation pipelines located upstream and downstream of the load device 39 are connected to purge and vacuum pipelines. The circulation pipeline is provided with a regulating member capable of regulating the flow rate of the refrigerant in the circulation pipeline; the liquid replenishment pipeline is connected to the circulation pipeline through the buffer tank 43, and the buffer tank 4 3 is also provided with a voltage stabilizing component, which can keep the refrigerant in the circulation pipeline in a supercooled state, and the liquid replenishing pipeline is also the same as the container; in this embodiment, the refrigerant is liquid nitrogen, the exhaust pipeline is used to discharge the nitrogen in the container, the exhaust pipeline is connected to the container, and a temperature sensor 21 and a nitrogen exhaust heater 20 are provided on the exhaust pipeline. The liquid nitrogen exhaust pipeline is used to discharge the liquid nitrogen in the circulation pipeline for easy evacuation and cleaning. In this embodiment, control valves are provided on the pipelines, and the controller is electrically connected to all control valves, and is electrically connected to the temperature sensor, liquid level meter, etc.

[0026] See also Figure 1 The container in this embodiment is a Dewar tank 40, which is a tank structure with an open top and a circumferentially closed structure. The top of the tank is fixedly connected by a Dewar tank cover plate, and is enclosed with the inner wall of the Dewar tank 40 to form a closed cavity structure. The Dewar tank cover plate is provided with a safety valve 8 connected to the cavity. The liquid replenishment pipeline includes a liquid nitrogen supply pipe 9, a first branch pipe, and a second branch pipe. The liquid nitrogen supply pipe 9 is provided with a filter 10. The liquid nitrogen supply pipe 9 is connected to the first branch pipe and the second branch pipe through a three-way interface, wherein the first branch pipe is connected to the buffer tank 43, a low-temperature switch valve 14 is provided on the first branch pipe, a low-temperature regulating valve 11 and a temperature sensor 2 are provided on the second branch pipe, and a Dewar tank level gauge 1 is provided on the Dewar tank 40.

[0027] See also Figure 1 A heat exchanger 38 is connected to the circulation pipeline, and the circulation pipeline includes a liquid supply pipeline 45 and a liquid return pipeline 46 that are connected to each other. Parts of the heat exchanger 38, the liquid supply pipeline 45 and the liquid return pipeline 46 are located below the liquid level of liquid nitrogen. One end of the liquid supply pipeline 45 is connected to one end of the heat exchanger 38, and the other end is connected to the input end of the load device 39. One end of the liquid return pipeline 46 is connected to the output end of the load device 39, and the other end is connected to the other end of the heat exchanger 38; the liquid supply pipeline 45 is provided with a flow meter 2 34, a low-temperature switch valve 35, and a temperature sensor 4 36 in sequence, and the liquid return pipeline 46 is provided with a temperature sensor 5 37, a low-temperature switch valve 5 30, and a flow meter 1 31 in sequence. The flow rate of the liquid return pipeline is measured by the flow meter 1 31, and the flow rate of the liquid supply pipeline is measured by the flow meter 2 34.

[0028] A bypass line 44 is also connected between the liquid supply line 45 and the liquid return line 46. The bypass line 44 is provided with a low-temperature regulating valve 2 33 and a temperature sensor 3 32. One end of the bypass line 44 is connected to the liquid supply line 45, and the other end of the bypass line 44 is connected to the liquid return line 46. The end of the bypass line 44 connected to the liquid supply line 45 is located upstream of the load device 39, and the end of the bypass line 44 connected to the liquid return line 46 is located downstream of the load device 39. The bypass line 44 forms a regulating member, and the bypass line 44 controls the flow of the liquid supply line 45, mainly for diversion. When it is necessary to reduce the liquid supply flow, the opening of the low-temperature regulating valve 2 33 can be increased to allow a part of the fluid in the liquid supply line to flow directly into the liquid return line 46, thereby reducing the flow of the liquid supply line 45 entering the load device 39, and vice versa.

[0029] The regulating member may also be a liquid nitrogen circulation pump 12 arranged on the circulation pipeline, and a second filter 41 is also arranged on the circulation pipeline, and the second filter 41 is located upstream of the liquid nitrogen circulation pump 12, and the second filter 41 can filter impurities. The motor frequency of the liquid nitrogen circulation pump 12 in this embodiment is adjustable, and the output frequency of the control motor of the liquid nitrogen circulation pump 12 can be used to adjust the speed of the liquid nitrogen circulation pump 12, thereby controlling the flow in the pipeline. Of course, a bypass pipeline 44, a second low-temperature regulating valve 33, a liquid nitrogen circulation pump 12, and a second filter 41 can also be arranged at the same time.

[0030] See also Figure 1 The pressure stabilizing component includes a low-temperature heating resistor 13 arranged in the buffer tank 43, and the low-temperature heating resistor 13 can heat the liquid nitrogen in the buffer tank 43, so as to carry out, the buffer tank 43 is also provided with a buffer tank level gauge 42 and a pressure sensor 16; the pressure stabilizing component can also be a pressurizing pipeline and a pressure relief pipeline connected to the buffer tank 43, wherein the pressurizing pipeline and the pressure relief pipeline are both provided with control valves, the end of the pressurizing pipeline forms a helium inlet 3, the pressurizing pipeline is provided with an electric valve 14, the pressure relief pipeline is provided with an electric valve 2 18, and the end of the pressure relief pipeline forms a helium exhaust The buffer tank 43 is also connected with a buffer tank evacuation pipeline, a buffer tank pressure relief pipeline, and a buffer tank exhaust pipeline. The buffer tank evacuation pipeline is connected to the buffer tank 43 and is provided with a ball valve 5, a purge and vacuum interface 6, a safety valve 19 and a safety bursting membrane 7 are provided on the buffer tank pressure relief pipeline, and a low-temperature switch valve 15 is provided on the buffer tank exhaust pipeline. When the system pressure is higher than the starting value of the safety valve, the safety valve will relieve the pressure. When the safety valve fails, the pressure will further rise. When the pressure is higher than the starting value of the safety bursting setting, the bursting membrane will burst and relieve the pressure.

[0031] The purge and vacuum pumping pipeline includes a first purge and vacuum pumping pipeline arranged upstream of the load device 39 and a second purge and vacuum pumping pipeline arranged downstream of the load device 39. The first purge and vacuum pumping pipeline is provided with a purge and vacuum pumping interface 3 27 and a ball valve 3 26. The first purge and vacuum pumping pipeline is also provided with a pressure sensor 28. The second purge and vacuum pumping pipeline is connected with a ball valve 22, a purge and vacuum pumping interface 23, and a safety valve 3 25. The second purge and vacuum pumping pipeline is provided with a safety bursting membrane 24. The purge and vacuum pumping interface 23 is connected to the second purge and vacuum pumping pipeline through a pipeline, and a ball valve 22 is provided on the pipeline. The safety valve 3 25 is connected to the second purge and vacuum pumping pipeline through another pipeline. A liquid nitrogen discharge pipeline is also connected to the circulation pipeline. A low-temperature switch valve 4 29 is provided on the liquid nitrogen discharge pipeline. The output end of the liquid nitrogen discharge pipeline is connected to the inner cavity of the Dewar tank 40.

[0032] Working principle:

[0033] 1. Purge and vacuum:

[0034] a. Mode 1:

[0035] Before the system is filled with liquid nitrogen, the entire closed-loop system needs to be purged and vacuumed to avoid the influence of impurities, air and moisture on the pipeline. By connecting 99.999% nitrogen to the purging and vacuuming interface 16, open the ball valve 15, the low-temperature switch valve 35, the low-temperature switch valve 5 30, and the ball valve 22, and close the low-temperature switch valve 14, the low-temperature switch valve 15, the low-temperature regulating valve 23, the low-temperature switch valve 4 29, the electric valve 14, the electric valve 218, and the ball valve 326 for purging. After purging for a period of time, close the ball valve 15 and the ball valve 22, connect the purging and vacuuming interface 23 to the vacuum pump, open the ball valve 22 to vacuum the system, and then close the ball valve 22, disconnect the vacuum pump, and complete the purging and vacuuming of the entire system;

[0036] b. Mode 1:

[0037] If the load device 39 needs to be replaced during system operation, it is only necessary to evacuate and purge the new load device 39 and some connecting pipelines by connecting 99.999% nitrogen to the purge and vacuum interface three 27, closing the low-temperature switch valve five 30, the low-temperature switch valve three 35, and the low-temperature switch valve four 29, and opening the ball valve two 22 and the ball valve three 26 to achieve the purge of the load device 39. After purging for a period of time, close the ball valve three 26 and the ball valve two 22, connect the purge and vacuum interface two 23 to the vacuum pump, open the ball valve two 22 to vacuum the system, and then close the ball valve two 22 and disconnect the vacuum pump to complete the purging and evacuation of the load device 39. When the experiment is over, the load device 39 can also be quickly warmed up in this way.

[0038] 2. System self-check:

[0039] When the system is filled with liquid nitrogen and starts to circulate, first close the low-temperature switch valve three 35 and the low-temperature switch valve five 30, and open the low-temperature regulating valve two 33 to realize the self-circulation of the system in the unit, cool itself first, and ensure the stable self-circulation operation of the system. When the temperature collected by the temperature sensor three 32 meets the requirements, the low-temperature switch valve three 35 and the low-temperature switch valve five 30 will be opened, and the opening of the low-temperature regulating valve two 33 will be reduced to supply cold capacity to the equipment.

[0040] 3. System operation:

[0041] After the supercooled liquid nitrogen in the pipeline is cooled by the heat exchanger 38, it is pumped to the load device 39 by means of the liquid nitrogen circulation pump 12. After the supercooled liquid nitrogen absorbs the heat of the load device 39, it returns to the heat exchanger 38. The supercooled liquid nitrogen basically circulates. In order to ensure the stable operation of the load equipment, it is necessary to ensure that the cooling capacity is balanced with the demand. Therefore, the cooling capacity needs to be adjusted in real time. When the heat load of the load end, that is, the load device 39, changes, the temperature sensor 5 37 will upload the temperature signal to the controller, and the controller will control the pipeline flow in real time. Two ways are designed to adjust the flow of the pipeline:

[0042] The first method is to control the flow of the liquid supply pipeline 45 through the bypass pipeline 44. When the liquid supply flow needs to be reduced, the opening of the low-temperature regulating valve 2 33 can be increased to allow part of the fluid in the liquid supply pipeline 45 to flow directly into the liquid return pipeline 46, thereby reducing the flow of the liquid supply pipeline 45, and vice versa.

[0043] The second method is to adjust the speed of the liquid nitrogen circulation pump 12 by controlling the output frequency of the motor, thereby controlling the flow in the pipeline, which can effectively reduce the temperature fluctuation of the working environment of the load device 39 and ensure its normal operation;

[0044] The pressure of the supercooled liquid nitrogen circulation pipeline is maintained above 2 bar, and the buffer tank 43 is used for pressure stabilization and liquid replenishment. The buffer tank 43 is connected to the circulation pipeline to achieve liquid replenishment to ensure that the pipeline is always full of supercooled liquid nitrogen; the buffer tank 43 is designed to stabilize the pressure in two ways:

[0045] The first method is to heat the liquid nitrogen through the low-temperature heating resistor 13, so that the liquid nitrogen itself vaporizes to increase the pressure in the buffer tank 43 and thus pressurize it; the second method is to introduce helium through the helium inlet 3. The boiling point of helium is very low, and it will always be a gas in the liquid nitrogen temperature zone. It is used to quickly pressurize the liquid nitrogen. By opening the electric valve 1 4, the system can be pressurized. The helium can also be discharged through the helium exhaust port 17 to achieve decompression. Open the electric valve 2 18 to discharge excess helium.

[0046] When the buffer tank level gauge 42 of the buffer tank 43 detects that the liquid level is lower than the set value, the controller will open the low-temperature switch valve 14 to replenish the liquid until the liquid level is higher than the safety value; if the pressure sensor 16 detects that the pressure of the circulation pipeline is too high, since the buffer tank 43 is connected to the circulation pipeline, the value of the pressure sensor 16 is the same as the pressure value of the circulation pipeline, and the low-temperature switch valve 15 can be opened to discharge nitrogen into the Dewar tank 40 and finally discharged from the tank body; the above method can be combined to quickly control the pressure of the liquid in the closed supercooled liquid nitrogen circulation pipeline to maintain the pressure in the pipeline stable;

[0047] When the Dewar tank liquid level gauge 1 of the Dewar tank 40 detects that the liquid level is lower than the set value, the low temperature regulating valve 11 is opened to replenish the liquid, and the replenishing temperature is measured by the temperature sensor. The filter 10 filters the injected liquid nitrogen, and the heat exchanger 38 is completely immersed in the liquid nitrogen of the Dewar tank 40, ensuring a good heat exchange effect.

[0048] The vaporized liquid nitrogen is heated by the nitrogen discharge heater 20 and then discharged. The nitrogen discharge heater 20 automatically adjusts the heating power according to the temperature collected by the temperature sensor at the outlet. When the outlet temperature is lower than the set value, the control system will increase the heating power to increase the discharge nitrogen temperature, and vice versa.

[0049] When the system needs to be warmed up, the liquid nitrogen in the circulation pipeline needs to be discharged by opening the low-temperature switch valve four 29, closing the low-temperature regulating valve two 33 and the low-temperature switch valve five 30, and using the liquid nitrogen circulation pump 12 to transport the liquid nitrogen to the Dewar tank 40, and then gasify and discharge it, and then open the ball valve one 5, the ball valve two 22, and the ball valve three 26, so that the residual liquid nitrogen in the pipeline can be discharged more quickly.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A supercooled liquid nitrogen cooling circulation system, characterized in that: The invention comprises a container containing a refrigerant and a circulation pipeline partially located in the container, wherein at least a portion of the circulation pipeline is located below the liquid level of the refrigerant in the container, the circulation pipeline is connected to a load device (39) and provides cooling therefor, the circulation pipeline located upstream and downstream of the load device (39) are connected to purge and vacuum pipelines, and the circulation pipeline is provided with a regulating member capable of regulating the flow rate of cooling mass in the circulation pipeline.

2. A supercooled liquid nitrogen cooling circulation system according to claim 1, characterized in that: It also includes a liquid replenishment pipeline and a buffer tank (43). The liquid replenishment pipeline is connected to the circulation pipeline through the buffer tank (43). A pressure stabilizing component is also provided in the buffer tank (43). The pressure stabilizing component can keep the refrigerant in the circulation pipeline in a supercooled state. The liquid replenishment pipeline is also the same as the container.

3. A supercooled liquid nitrogen cooling circulation system according to claim 1, characterized in that: The circulation pipeline is connected to a heat exchanger (38), and the circulation pipeline comprises a liquid supply pipeline (45) and a liquid return pipeline (46) which are connected to each other. One end of the liquid supply pipeline (45) is connected to one end of the heat exchanger (38), and the other end is connected to the input end of a load device (39). One end of the liquid return pipeline (46) is connected to the output end of the load device (39), and the other end is connected to the other end of the heat exchanger (38).

4. The supercooled liquid nitrogen cooling circulation system according to claim 1, characterized in that: The regulating component comprises a liquid nitrogen circulation pump (12) arranged on a circulation pipeline. A second filter (41) is also arranged on the circulation pipeline. The second filter (41) is located upstream of the liquid nitrogen circulation pump (12).

5. The supercooled liquid nitrogen cooling circulation system according to claim 3, characterized in that: The regulating member comprises a bypass pipeline (44), one end of the bypass pipeline (44) is connected to a liquid supply pipeline (45), and the other end of the bypass pipeline (44) is connected to a liquid return pipeline (46), and the end of the bypass pipeline (44) connected to the liquid supply pipeline (45) is located upstream of the load device (39), and the end of the bypass pipeline (44) connected to the liquid return pipeline (46) is located downstream of the load device (39).

6. The supercooled liquid nitrogen cooling circulation system according to claim 2, characterized in that: The voltage stabilizing component comprises a low-temperature heating resistor (13) arranged in a buffer tank (43). The buffer tank (43) is also provided with a buffer tank liquid level meter (42) and a pressure sensor (16). The container is provided with a liquid level meter.

7. The supercooled liquid nitrogen cooling circulation system according to claim 2, characterized in that: The pressure stabilizing assembly comprises a pressurizing pipeline and a pressure relief pipeline connected to the buffer tank (43), and the pressurizing pipeline and the pressure relief pipeline are both provided with control valves.

8. The supercooled liquid nitrogen cooling circulation system according to claim 1, characterized in that: The container is also connected to an exhaust pipeline, which is in communication with the container and is provided with a second temperature sensor (21) and a nitrogen exhaust heater (20).

9. The supercooled liquid nitrogen cooling circulation system according to claim 1, characterized in that: The purge and vacuum pumping pipeline comprises a first purge and vacuum pumping pipeline arranged upstream of the load device (39) and a second purge and vacuum pumping pipeline arranged downstream of the load device (39), wherein the first purge and vacuum pumping pipeline is provided with a purge and vacuum pumping interface three (27), and the second purge and vacuum pumping pipeline is provided with a ball valve two (22), a purge and vacuum pumping interface two (23), and a safety valve three (25).

10. The supercooled liquid nitrogen cooling circulation system according to claim 1, characterized in that: The circulation pipeline is also connected to a liquid nitrogen discharge pipeline, and a low-temperature switch valve four (29) is arranged on the liquid nitrogen discharge pipeline. The output end of the liquid nitrogen discharge pipeline is connected to the inner cavity of the container.

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